Mixer having phase shift function and communications device including the same

ABSTRACT

A mixer includes a load portion connected between an input terminal of a first power voltage and an output terminal of the radio frequency transmit signal and configured to adjust a magnitude of the radio frequency transmit signal, a first switching unit connected to an output terminal of the radio frequency transmit signal, and configured to perform a first switching operation in response to a plurality of local oscillation signals, and a second switching unit connected between the first switching unit and an input terminal of a second power voltage, lower than the first power voltage, and configured to perform a second switching operation in response to a plurality of baseband signals, the plurality of local oscillation signals include an I+ baseband signal, an I− baseband signal, a Q+ baseband signal, and a Q− baseband signal, and the second switching unit includes a first branch performing a switching operation under control of the I+ baseband signal and the Q+ baseband signal, a second branch performing a switching operation under control of the I− baseband signal and the Q− baseband signal, a third branch performing a switching operation under control of the Q+ baseband signal and the I− baseband signal, and a fourth branch performing a switching operation under control of the Q− baseband signal and the I+ baseband signal.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119 to Korean PatentApplication No. 10-2019-0127290 filed on Oct. 14, 2019 in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein by reference in its entirety.

TECHNICAL FIELD

The present inventive concept relates to a mixer having a phase shiftfunction, and a communications device including the same.

DISCUSSION OF RELATED ART

Research and development of next generation wireless communicationstechniques using an extremely high frequency band have been activelyconducted. For example, to alleviate loss in a transmission path of anextremely high frequency signal and to increase a transmission distance,techniques such as beamforming, a massive multi-input multi-output(massive MIMO), a full dimensional MIMO (FD-MIMO), an array antenna, anda large-scale antenna have been discussed.

Among such next generation wireless communications techniques, abeamforming technique is used to increase communications efficiency byconcentrating an extremely high frequency signal in a certain direction.To perform a beamforming technique, a phase shifter might be used. Whena phase shifter operates in an extremely high frequency band, signalloss might increase such that a deterioration of performance mightresult, such as manifested by an increase of gain, an increase ofcurrent consumption, an increase of chip area, or the like.

SUMMARY

An exemplary embodiment of the present inventive concept provides amixer which may shift a phase of a radio frequency (RF) signal withoutusing a phase shifter, and a communications device including the same.

According to an exemplary embodiment of the present inventive concept, amixer includes a load portion connected between an input terminal of afirst power voltage and an output terminal of the radio frequencytransmit signal and configured to adjust a magnitude of the radiofrequency transmit signal, a first switching unit connected to an outputterminal of the radio frequency transmit signal, and configured toperform a first switching operation in response to a plurality of localoscillation signals, and a second switching unit connected between thefirst switching unit and an input terminal of a second power voltage,lower than the first power voltage, and configured to perform a secondswitching operation in response to a plurality of baseband signals, theplurality of local oscillation signals include an I+ baseband signal, anI− baseband signal, a Q+ baseband signal, and a Q− baseband signal, andthe second switching unit includes a first branch performing a switchingoperation under control of the I+ baseband signal and the Q+ basebandsignal, a second branch performing a switching operation under controlof the I− baseband signal and the Q− baseband signal, a third branchperforming a switching operation under control of the Q+ baseband signaland the I− baseband signal, and a fourth branch performing a switchingoperation under control of the Q− baseband signal and the I+ basebandsignal.

According to an exemplary embodiment of the present inventive concept, acommunications device includes a modulator configured to generate aplurality of first baseband signals by modulating a transmit bitstream,a local oscillation signal generator configured to generate a pluralityof first local oscillation signals and to generate a plurality of secondlocal oscillation signals phase-shifted by a first phase value withrespect to the plurality of first local oscillation signals bymultiplexing the plurality of first local oscillation signals, and amixer configured to generate a radio frequency transmit signal byup-conversion of the plurality of first baseband signals using theplurality of second local oscillation signals, and the mixer isconfigured to generate a plurality of second baseband signalsphase-shifted by a second phase value with respect to the plurality offirst baseband signals by combining the plurality of first basebandsignals and to perform a mixing operation with respect to the pluralityof second baseband signals and the plurality of second local oscillationsignals.

According to an exemplary embodiment of the present inventive concept, acommunications device includes a modem configured to generate a transmitbaseband signal by modulating a transmit bitstream, and to demodulate areceive baseband signal to a receive bitstream, a transmitter circuitconfigured to generate a radio frequency transmit signal by frequencyup-conversion of the transmit baseband signal using a transmit localoscillation signal, and a receiver circuit configured to generate thereceive baseband signal by frequency down-conversion of a radiofrequency receive signal using a receive local oscillation signal, thetransmit local oscillation signal and the receive local oscillationsignal are obtained by phase-shifting a quadrature signal, and thetransmitter circuit is configured to perform the frequency up-conversionfor the phase-shifted transmit baseband signal after phase-shifting thetransmit baseband signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects of the present inventive concept will bemore clearly understood from the following detailed description, takenin conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram illustrating a wireless communicationssystem according to an exemplary embodiment of the present inventiveconcept;

FIG. 2 is a block diagram illustrating a communications device accordingto an exemplary embodiment of the present inventive concept;

FIG. 3 is a hybrid diagram illustrating a transceiver according to anexemplary embodiment of the present inventive concept;

FIG. 4 is a circuit diagram illustrating part of a local oscillationsignal generator of FIG. 3;

FIG. 5 is a circuit diagram illustrating a multiplexer of FIG. 4;

FIG. 6 is a tabular diagram illustrating a multiplexer of FIG. 4;

FIGS. 7A, 7B, 7C and 7D are phase-offset signal diagrams for amultiplexer of FIG. 4;

FIG. 8 is a circuit diagram illustrating a multiplexer of FIG. 4;

FIG. 9 is a circuit diagram illustrating a structure of a mixeraccording to an exemplary embodiment of the present inventive concept;

FIGS. 10A and 10B are phase diagrams illustrating a method of collectingbaseband signals and performing phase-shifting by a mixer according toan exemplary embodiment of the present inventive concept;

FIG. 11 is a circuit diagram illustrating a structure of a mixeraccording to an exemplary embodiment of the present inventive concept;

FIG. 12 is a flowchart diagram illustrating a method of operating acommunications device according to an exemplary embodiment of thepresent inventive concept;

FIG. 13 is a flowchart diagram illustrating a method of operating acommunications device according to an exemplary embodiment of thepresent inventive concept;

FIG. 14 is a schematic diagram illustrating an electronic deviceincluding a communications device according to an exemplary embodimentof the present inventive concept;

FIG. 15 is a conceptual diagram illustrating an application of acommunications device according to an exemplary embodiment of thepresent inventive concept; and

FIG. 16 is a conceptual diagram illustrating an application of acommunications device according to an exemplary embodiment of thepresent inventive concept.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present inventive concept willbe described with reference to the accompanying drawings. It shall beunderstood that such exemplary embodiments are illustrative of, butlimiting to, the present inventive concept.

FIG. 1 illustrates a wireless communications system according to anexemplary embodiment of the present disclosure.

Referring to FIG. 1, a wireless communications system 1 may include aplurality of communications devices 10-1 to 10-6, each performingwireless communications using a transceiver. The wireless communicationssystem 1 may include a 4th generation (4G) network system such as along-term evolution (LTE) system, or the like, a 5th generation (5G)network system supporting a new radio (NR) protocol prescribed in 3GPP,or the like.

Some of the plurality of communications devices 10-1 to 10-6 may be basestations (BS), and the others may be user equipment (UE). The BS may bea subject communicating with the UE, and may be referred to as a basetransceiver station (BTS), a node b (NB), an evolved-node b (eNB),access point (AP), or the like. The UE may be a subject communicatingwith a BS and/or other UEs, and may be referred to as a mobile station(MS), mobile equipment (ME), a terminal, or the like. FIG. 1 illustratesan example in which the first communications device 10-1 is implementedas a BS, and the second to sixth communications devices 10-2 to 10-6 areimplemented as UEs. However, embodiments thereof are not limitedthereto.

The plurality of communications devices 10-1 to 10-6 may performwireless communications using a wireless signal having a wavelength ofan ultrahigh frequency band. For example, the plurality ofcommunications devices 10-1 to 10-6 may perform wireless communicationsusing a millimeter wave (mmWave) having a wavelength of 1 mm to 100 mmcorresponding to a wireless frequency of 3 GHz to 300 GHz. The pluralityof communications devices 10-1 to 10-6 may also perform wirelesscommunications using a wave of terahertz band.

The plurality of communications devices 10-1 to 10-6 may performbeamforming to reduce signal loss caused by channel propagationproperties of an ultrahigh frequency band.

The beamforming may be divided into transmission beamforming performedby transmitters of the communications devices 10-1 to 10-6 and receptionbeamforming performed by receivers of the communications devices 10-1 to10-6. The plurality of communications devices 10-1 to 10-6 may performtransmission beamforming using a plurality of antennas and mayconcentrate a reaching area (hereinafter, referred to as a beam area) ofa signal in a certain direction, thereby increasing directivity of thesignal. As the plurality of communications devices 10-1 to 10-6increases directivity of a signal by performing transmissionbeamforming, the plurality of communications devices 10-1 to 10-6 mayincrease a reaching distance of a signal and may decrease signalinterference. Also, the plurality of communications devices 10-1 to 10-6may perform reception beamforming using a plurality of antennas and mayconcentrate a reception direction of a signal in a certain direction,thereby increasing reception sensitivity and reducing signalinterference.

Referring to FIG. 1, the first communications device 10-1 may transmit afirst wireless signal having a first beam area BA1 and a second wirelesssignal having a second beam area BA2. As the second communicationsdevice 10-2 and the third communications device 10-3 are included in thefirst beam area BA1, the second communications device 10-2 and the thirdcommunications device 10-3 may receive the first wireless signal. Also,as the fifth communications device 10-5 and the sixth communicationsdevice 10-6 are included in the second beam area BA2, the fifthcommunications device 10-5 and the sixth communications device 10-6 mayreceive the second wireless signal. However, as the third communicationsdevice 10-3 is not included in either of the first beam area BA1 or thesecond beam area BA2, the third communications device 10-3 may notreceive the first wireless signal or the second wireless signal.

The plurality of communications devices 10-1 to 10-6 may performbeamforming using a plurality of radio frequency (RF) signals having acertain phase difference therebetween. Generally, a plurality ofcommunications devices might use a phase shifter to generate theplurality of RF signals having a certain phase difference therebetween.However, when a phase shifter is used, signal loss may increase suchthat performance deterioration, such as a decrease of a gain, anincrease of current consumption, an increase of a chip area, or thelike, may occur. Thus, the communications device of the exemplaryembodiment may multiplex a local oscillation signal to a quadraturesignal and may input the quadrature signal to a mixer, and mayphase-shift a baseband signal on a source terminal of the mixer, therebygenerating a plurality of RF signals having a certain phase differencetherebetween without using a phase-shifter.

FIG. 2 illustrates a communications device according to an exemplaryembodiment of the present disclosure.

Referring to FIG. 2, a communications device 10 may include a controller100, a storage 200 connected to at least one of the controller or atransceiver, and a transceiver 300 connected to at least one of thecontroller or the storage.

The controller 100 may control overall operations of the communicationsdevice 10. For example, the controller 100 may control the transceiver300 for the communications device 10 to transmit and receive an RFsignal. In an exemplary embodiment, the controller 100 may control thetransceiver 300 to generate a plurality of RF signals having a certainphase difference therebetween to perform transmission beamforming. Thecontroller 100 may also control the transceiver 300 to selectivelyactivate at least some of a plurality of antennas to perform receptionbeamforming. The controller 100 may include at least one processor ormicroprocessor.

The storage 200 may store various data required for operation of thecommunications device 10. For example, the storage 200 may store variousprograms and setting information required for wireless communication.The storage 200 may be implemented by a non-volatile memory such as aNAND flash memory, or the like, a volatile memory such as a DRAM, or thelike, or a combination of a non-volatile memory and a volatile memory.

The transceiver 300 may transmit an RF signal to and receive an RFsignal from other communications devices through a plurality ofantennas. For example, the transceiver 300 may perform frequencyup-conversion of a baseband signal to an RF signal, and may transmit anRF signal through the plurality of antennas. The transceiver 300 mayalso perform frequency down-conversion of an RF signal received throughthe plurality of antennas to a baseband signal.

To perform such a wireless communications function, the transceiver 300may include a modem, a filter, a mixer, an amplifier, or the like. Thetransceiver 300 may also include a plurality of antennas. The collectionof the plurality of antennas may be referred to as an antenna array, andeach of the plurality of antennas included in the antenna array may bereferred to as an array element. The antenna array may be implemented asvarious types of antenna arrays, such as a linear array, a planar array,or the like.

FIG. 2 illustrates an example in which the transceiver 300 isimplemented as a single element including a transmitter and a receiverintegrated with each other, but embodiments thereof are not limitedthereto. For example, the transceiver 300 may include a transmitter anda receiver separated from each other. In the description below, thetransceiver 300 will be described in greater detail with reference toFIG. 3.

FIG. 3 illustrates a transceiver according to an exemplary embodiment ofthe present disclosure.

Referring to FIG. 3, a transceiver 300 may include a modem 310, atransmitter circuit 330, transmit amplifiers 341 and 343, receiveamplifiers 361 and 363, a receiver circuit 370, and an antenna array350.

The modem 310 may include a modulator 311 and a demodulator 313, and mayinterconvert a baseband signal and a bitstream in accordance with aphysical layer specification of a system.

The modulator 311 may modulate a transmit bitstream and may generate atransmit baseband signal BBI and BBQ. The transmit baseband signal BBIand BBQ may be a digital signal, and may be a quadrature signalincluding an in-phase (I-phase) baseband signal BBI of a real numberarea and a quadrature-phase (Q-phase) baseband signal BBQ of animaginary area. The I− phase baseband signal BBI may include an I+baseband signal BBIp and an I− baseband signal BBIn having a phasedifference of 180 degrees therebetween. The Q− phase baseband signal BBQmay include a Q+ baseband signal BBQp and a Q− baseband signal BBQnhaving a phase difference of 180 degrees therebetween.

The demodulator 313 may demodulate a receive baseband signal RBBI′ andRBBQ′ and may recover a receive bitstream. The receive baseband signalRBBI′ and RBBQ′ may be a digital signal, and may include an I-phasebaseband signal RBBI′ and a Q-phase baseband signal RBBQ′. The I-phasebaseband signal RBBI′ may include an I+ baseband signal RBBIp′ and an I−baseband signal RBBIn′. Also, a Q-phase baseband signal RBBQ′ mayinclude a Q+ baseband signal RBBQp′ and a Q− baseband signal RBBQn′.

A local oscillation signal generator 320 may generate a localoscillation signal, may multiplex the generated local oscillationsignal, and may provide the multiplexed oscillation signal to thetransmitter circuit 330 and the receiver circuit 370. A specificconfiguration and an operation method of the local oscillation signalgenerator 320 are illustrated in FIGS. 4 and 8.

The transceiver may selectively activate a plurality of antennas orantenna elements with a plurality of phase shifts to perform receptionbeamforming for a receive signal from a certain direction. Thetransceiver 300 may include a receive mixer 371 configured to generate aplurality of first baseband receive signals RBBIp, RBBIn, RBBOp andRBBQn by down-conversion of a plurality of radio frequency receivesignals RXp and RXn using a plurality of second local oscillationsignals LOIp′, LOIn′, LOQp′ and LOQn′. The transceiver may be configuredto generate a plurality of second baseband receive signals RBBIp′,RBBIn′, RBBOp′ and RBBQn′ phase-shifted by a phase value with respect tothe plurality of first baseband receive signals RBBIp, RBBIn, RBBQp andRBBQn by combining the plurality of first baseband receive signals andperforming a mixing operation with respect to the plurality of secondbaseband receive signals using the plurality of second local oscillationsignals and the plurality of first local oscillation signals LOIp, LOIn,LOQp and LOQn. The plurality of first baseband receive signals may beanalog signals and the plurality of second baseband receive signals maybe digital signals.

FIGS. 4 to 8 collectively illustrate a local oscillation signalgenerator according to an exemplary embodiment of the presentdisclosure.

Referring to FIG. 4, a local oscillation signal generator 400 mayinclude a local oscillator 410 and a local oscillation (LO) buffer 430.

The local oscillator 410 may generate a plurality of quadrature signalsLOIp, LOIn, LOQp, and LOQn as local oscillation signals. In an exemplaryembodiment, the local oscillator 410 may include a voltage-controlledoscillator (VCO).

The LO buffer 430 may shift phases of the plurality of local oscillationsignals LOIp, LOIn, LOQp, and LOQn by multiplexing the plurality oflocal oscillation signals LOIp, LOIn, LOQp, and LOQn generated by thelocal oscillator 410. In an exemplary embodiment, phase-shift values ofthe plurality of local oscillation signals LOIp, LOIn, LOQp, and LOQnmay be 90-degree units (which are, 0, 90, 180, and 270 degrees).

The LO buffer 430 may include a first LO multiplexing unit 431outputting local oscillation signals LOIp and LOIn of an I-phase and asecond LO multiplexing unit 433 outputting local oscillation signalsLOQp and LOQn of a Q-phase. FIG. 4 illustrates an example in which theLO buffer 430 includes the first LO multiplexing unit 431 and the secondLO multiplexing unit 433, but an exemplary embodiment thereof is notlimited thereto. For example, the LO buffer 430 may include four LOmultiplexing units outputting the plurality of local oscillation signalsLOIp, LOIn, LOQp, and LOQn, respectively.

FIGS. 5 to 7D illustrate an example of the first and second LOmultiplexing units 431 and 433 illustrated in FIG. 4.

Referring to FIG. 5, an LO multiplexing unit 500 may be implemented as amultiplexer MUX. The LO multiplexer 500 may select one of a plurality ofinput signals as one of I-phase and Q-phase local oscillation signals,thereby outputting a phase-shifted local oscillation signal. Forexample, when the LO multiplexing unit 500 is implemented as a 4×1multiplexer, the LO multiplexing unit 500 may receive a plurality oflocal oscillation signals LOIp, LOIn, LOQp, and LOQn from a localoscillator as first to fourth input signals in1 to in4, and may selectone of the first to fourth input signals in1 to in4 as an I+ localoscillation signal LOIp on the basis of first and second control signalsS0 and S1 and may output the selected signal.

In an exemplary embodiment, the local oscillation signals LOIp, LOIn,LOQp, and LOQn, determined as an output signal out, may be phase-shiftedin accordance with a result of signal selection based on combination ofthe local oscillation signals LOIp, LOIn, LOQp, and LOQn and the controlsignals S0 and S1 as the input signals in1 to in4.

The combination of the local oscillation signals LOIp, LOIn, LOQp, andLOQn as the input signals in1 to in4, and the phase-shifting of thelocal oscillation signals LOIp′, LOIn′, LOQp′, and LOQn′ as the outputsignals out are illustrated in FIG. 6.

Referring to FIG. 6 along with FIG. 5, in a first case, an I+ localoscillation signal LOIp, a Q+ local oscillation signal LOQp, an I− localoscillation signal LOIn, and a Q− local oscillation signal LOQn may beinput to an LO multiplexing unit 500 in order as input signals in1 toin4. Also, the LO multiplexing unit 500 may set the I+ local oscillationsignal LOIp′ as an output signal out. The above-described operation maybe implemented by connecting an output terminal of the LO multiplexingunit 500 to a source terminal of the I+ local oscillation signal LOIp′of a mixer.

When the first control signal S0 is “0” (or a logic low), and the secondcontrol signal S1 is “0,” the LO multiplexing unit 500 may select the I+local oscillation signal LOIp, the first input signal in1. As there isno phase difference between the selected signal and the I+ localoscillation signal LOIp, the first input signal in1, the phase-shiftingof the I+ local oscillation signal LOIp′ may not occur as in FIG. 7A.

When the first control signal S0 is “0,” and the second control signalS1 is “1,” the LO multiplexing unit 500 may select the Q+ localoscillation signal LOQp, the second input signal in2. As a phasedifference between the selected signal and the I+ local oscillationsignal LOIp, and an output signal out, is 90 degrees, the I+ localoscillation signal LOIp′ may be phase-shifted by 90 degrees as in FIG.7B.

When the first control signal S0 is “1,” and the second control signalS1 is “0,” the LO multiplexing unit 500 may select the I− localoscillation signal LOIn, a third input signal in3. As a phase differencebetween the selected signal and the I+ local oscillation signal LOIp,and an output signal out, is 180 degrees, the I+ local oscillationsignal LOIp′ may be phase-shifted by 180 degrees as in FIG. 7C.

When the first control signal S0 is “1,” and the second control signalS1 is “1,” the LO multiplexing unit 500 may select the Q− localoscillation signal LOQn, a fourth input signal in4. As a phasedifference between the selected signal and the I+ local oscillationsignal LOIp, and an output signal out, is 270 degrees, the I+ localoscillation signal LOIp′ may be phase-shifted by 270 degrees as in FIG.7D.

In a second case, the I− local oscillation signal LOIn, the Q− localoscillation signal LOQn, the I+ local oscillation signal LOIp, and theQ+ local oscillation signal LOQp may be input to the LO multiplexingunit 500 in order as the first to fourth input signals in1 to in4. TheLO multiplexing unit 500 may set the I− local oscillation signal LOIn′as an output signal out. The above-described operation may beimplemented by connecting an output terminal of the LO multiplexing unit500 to a source terminal of the I− local oscillation signal LOIn′ of amixer.

As in the first case, when the first control signal S0 is “0,” and thesecond control signal S1 is “0,” the phase-shifting of the I− localoscillation signal LOIn′, an output signal out, may not occur. When thefirst control signal S0 is “0,” and the second control signal S1 is “1,”the I− local oscillation signal LOIn′, an output signal out, may bephase-shifted by 90 degrees. When the first control signal S0 is “1,”and the second control signal S1 is “0,” the I− local oscillation signalLOIn′, an output signal out, may be phase-shifted by 180 degrees. Whenthe first control signal S0 is “1,” and the second control signal S1 is“1,” the I− local oscillation signal LOIn′, an output signal out, may bephase-shifted by 270 degrees.

In a third case, the Q+ local oscillation signal LOQp, the I− localoscillation signal LOIn, the Q− local oscillation signal LOQn, and theI+ local oscillation signal LOIp may be input to the LO multiplexingunit 500 in order as the first to fourth input signals in1 to in4. Also,the LO multiplexing unit 500 may set the Q+ local oscillation signalLOQp′ as an output signal out. The above-described operation may beimplemented by connecting an output terminal of the LO multiplexing unit500 to a source terminal of the Q+ local oscillation signal LOQp′ of amixer.

As in the first case, when the first control signal S0 is “0,” and thesecond control signal S1 is “0,” the phase-shifting of the Q+ localoscillation signal LOQp′, an output signal out, may not occur. When thefirst control signal S0 is “0,” and the second control signal S1 is “1,”the Q+ local oscillation signal LOQp′, an output signal out, may bephase-shifted by 90 degrees. When the first control signal S0 is “1,”and the second control signal S1 is “0,” the Q+ local oscillation signalLOQp′, an output signal out, may be phase-shifted by 180 degrees. Whenthe first control signal S0 is “1,” and the second control signal S1 is“1,” the Q+ local oscillation signal LOQp′, an output signal out may bephase-shifted by 270 degrees.

In a fourth case, the Q− local oscillation signal LOQn, the I+ localoscillation signal LOIp, the Q+ local oscillation signal LOQp, and theI− local oscillation signal LOIn may be input to the LO multiplexingunit 500 in order as the first to fourth input signals in1 to in4. Also,the LO multiplexing unit 500 may set the Q− local oscillation signalLOQn′ as an output signal output. The above-described operation may beimplemented by connecting an output terminal of the LO multiplexing unit500 to a source terminal of the Q− local oscillation signal LOQn′ of amixer.

As in the first case, when the first control signal S0 is “0,” and thesecond control signal S1 is “0,” the phase-shifting of the Q− localoscillation signal LOQn′, an output signal out, may not occur. When thefirst control signal S0 is “0,” and the second control signal S1 is “1,”the Q− local oscillation signal LOQn′, an output signal out may bephase-shifted by 90 degrees. When the first control signal S0 is “1,”and the second control signal S1 is “0,” the Q− local oscillation signalLOQn′, an output signal out, may be phase-shifted by 180 degrees. Whenthe first control signal S0 is “1,” and the second control signal S1 is“1,” the Q− local oscillation signal LOQn′, an output signal out may bephase-shifted by 270 degrees.

A transceiver in the exemplary embodiment may multiplex a localoscillation signal on an LO buffer terminal before a mixer and mayperform the phase-shifting of 90 degrees, thereby endowing aphase-shifting function to the mixer. Also, by not performing themultiplexing of a local oscillation signal on a main signal path, signalloss may be prevented and a gain may increase.

FIG. 8 illustrates another example of the first and second LOmultiplexing units 431 and 433.

Referring to FIG. 8, an LO multiplexing unit 600 may be implemented bycombination of a plurality of buffers BUF. The LO multiplexing unit 600may include a plurality of buffer paths P1 to P4 activated in responseto a plurality of control signals S00 to S11. A plurality of differentlocal oscillation signals LOIp, LOIn, LOQp, and LOQn may be input to theplurality of buffer paths P1 to P4, and the LO multiplexing unit 600 mayperform the phase-shifting of the local oscillation signals LOIp′,LOIn′, LOQp′, and LOQn′ determined as output signals out by selectingone of the local oscillation signals input in response to the pluralityof control signals S00 to S11. The above-described operation may beimplemented by connecting an output terminal of the LO multiplexing unit600 to a source terminal of a certain local oscillation signal of amixer.

For example, the LO multiplexing unit 600 may include a first bufferpath P1 including a plurality of buffers BUF operating in response to afirst control signal S00, a second buffer path P2 including a pluralityof buffers BUF operating in response to a second control signal SOL athird buffer path P3 including a plurality of buffers BUF operating inresponse to a third control signal S10, and a fourth buffer path P4including a plurality of buffer BUF operating in response to a fourthcontrol signal S11.

The phase-shifting of the local oscillation signals LOIp′, LOIn′, LOQp′,and LOQn′, output signals out, may occur in accordance with combinationof the plurality of local oscillation signals LOIp, LOIn, LOQp, and LOQninput to the first to fourth buffer paths P1 to P4, and an activatedstatus of the first to fourth buffer paths P1 to P4 on the basis of thefirst to fourth control signals S00 to S11. In an exemplary embodiment,the LO multiplexing unit 600 may phase-shift the plurality of localoscillation signals LOIp, LOIn, LOQp, and LOQn by 90-degree units andmay output the signals LOIp′, LOIn′, LOQp′, and LOQn′.

For example, when the I+ local oscillation signal LOIp, the Q+ localoscillation signal LOQp, the I− local oscillation signal LOIn, and theQ− local oscillation signal LOQn are input to the first to fourth bufferpaths P1 to P4 in order, as there is no phase different between the I+local oscillation signal LOIp input to the activated first buffer pathP1 and the I+ local oscillation signal LOIp′ determined as an outputsignal out, the phase-shifting of the I+ local oscillation signal LOIpmay not occur. Also, as a phase difference between the Q+ localoscillation signal LOQp input to the activated second buffer path P2 andthe I+ local oscillation signal LOIp′ determined as an output signal outis 90 degrees, the I+ local oscillation signal LOIp′ may bephase-shifted by 90 degrees. In other exemplary embodiments, the LOmultiplexing unit 600 may occur the phase-shifting of an output signalout by the method the same as described above, which may be easilyderived from the exemplary embodiments described with reference to FIGS.5 to 7D.

For ease of description, referring back to FIG. 3, a transmitter circuit330 may generate RF transmit signals TXp and TXn by frequencyup-conversion of an I-phase baseband signal BBI′ and a Q-phase basebandsignal BBQ′, converted to analog signals.

The transmitter circuit 330 may include a digital-analog converter 331,an analog filter 333, and a mixer 335.

The digital-analog converter 331 may convert an I-phase baseband signalBBI and a Q-phase baseband signal BBQ output from a modulator 311 toanalog signals.

The analog filter 333 may perform the frequency-filtering of the I-phasebaseband signal BBI′ and the Q-phase baseband signal BBQ′ converted toanalog signals. In an exemplary embodiment, the analog filter 333 mayinclude a low pass filter (LPF).

The mixer 335 may perform up-conversion of frequencies of a plurality ofbaseband signals BBI′ and BBQ′ received from the analog filter 333 usingthe plurality of local oscillation signals LOIp′, LOIn′, LOQp′, andLOQn′ received from the local oscillation signal generator 320.

In an exemplary embodiment, the mixer 335 may perform a mixing operationusing the plurality of phase-shifted plurality of local oscillationsignals LOIp′, LOIn′, LOQp′, and LOQn′, thereby providing aphase-shifting function with respect to the RF signals TXp and TXn,output signals. For example, the mixer 335 may perform a mixingoperation using the plurality of local oscillation signals LOIp′, LOIn′,LOQp′, and LOQn′ phase-shifted by 90-degree units by the localoscillation signal generator 320, thereby generating the RF signals TXpand TXn each having a phase-shift of 90-degree units.

In an exemplary embodiment, the mixer 335 may perform a mixing operationby combining the plurality of baseband signals BBI′ and BBQ′ receivedfrom the analog filter 333, thereby providing a phase-shifting functionwith respect to the RF signals TXp and TXn, output signals. For example,the mixer 335 may perform a mixing operation using a signal obtained bycombining

$\frac{1}{\sqrt{2}}$

times the I+ baseband signal BBIp′ and

$\frac{1}{\sqrt{2}}$

times the Q+ baseband signal BBQp′, received from the analog filter 333,thereby generating the first and second RF signals TXp and TXn eachhaving a phase-shift of 45 degrees.

In this case, the first RF signal TXp output from the mixer 335 may betransferred to a first transmit amplifier 341. The first transmitamplifier 341 may amplify the first RF signal TXp and may output theamplified first RF signal TXp to an antenna 350. Also, the second RFsignal TXn output from the mixer 335 may be transferred to a secondtransmit amplifier 343. The second transmit amplifier 343 may amplifythe second RF signal TXn and may output the amplified second RF signalTXn to the antenna 350. The first RF signal TXp and the second RF signalTXn may have a phase different of 180 degrees therebetween.

In an exemplary embodiment, the first and second transmit amplifiers 341and 343 may include a power amplifier.

The antenna 350 may externally transmit the first and second RF signalsTXp and TXn transferred from the transmitter circuit 330 through thefirst and second transmit amplifiers 341 and 343. The antenna 350 maytransmit the first and second RF signals TXp and TXn as omnidirectionalsignals, or may form at least one beam B1 to B3 having directivity usingthe first and second RF signals TXp and TXn and may transmit(beamforming) the beam in a certain direction.

The antenna 350 may be implemented as an array antenna to performbeamforming. The array antenna may include a plurality of antennaelements 351, and a communications device 300 may selectively activatethe plurality of antenna elements 351 and may perform beamforming. FIG.3 illustrates the example in which the antenna 350 is implemented as aplanar array antenna, but an exemplary embodiment thereof is not limitedthereto. For example, the antenna 350 may have various structures, alinear array antenna, or the like.

The plurality of RF signals RXp and RXn received from an external entitythrough the antenna 350 may be amplified by receive amplifiers 361 and363, and may be transferred to a receiver circuit 370. For example, thefirst RF signal RXp received through the antenna 350 may be amplified bythe first receive amplifier 361, and may be transferred to the receivercircuit 370. Also, the second RF signal RXn received through the antenna350 may be amplified by the second receive amplifier 363, and may betransferred to the receiver circuit 370. The first RF signal RXp and thesecond RF signal RXn may have a phase difference of 180 degrees.

In an exemplary embodiment, the first receive amplifier 361 and thesecond receive amplifier 363 may include a low noise amplifier (LNA).

The receiver circuit 370 may include a mixer 371, an analog filter 373,and an analog-digital converter 375.

The mixer 371 may perform frequency down-conversion of the plurality ofRF signals RXp and RXn received from the receive amplifiers 361 and 363using the plurality of local oscillation signals LOIp′, LOIn′, LOQp′,and LOQn′ received from the local oscillation signal generator 320,thereby generating a plurality of baseband signals RBBI and RBBQ. Thegenerated baseband signals RBBI and RBBQ may be quadrature signals, mayinclude an I-phase baseband signal RBBIp and RBBIn and a Q-phasebaseband signal RBBQp and RBBQn.

The analog filter 373 may perform a frequency filtering operation withrespect to the baseband signals RBBI and RBBQ received from a mixer 371.In an exemplary embodiment, the analog filter 373 may include a low passfilter (LPF).

The analog-digital converter 375 may convert the baseband signals RBBIand RBBQ to digital signals. The baseband signals RBBI′ and RBBQ′converted to digital signals may be transferred to a multiplexer 313 andmay be recovered to a receive bitstream through a multiplexing process.

In the description below, a mixer will be described in greater detail inaccordance with an exemplary embodiment with reference to FIGS. 9 to 11.

FIG. 9 illustrates a structure of a mixer according to an exemplaryembodiment of the present disclosure. FIGS. 10A and 10B illustrate amethod of collecting baseband signals and performing phase-shifting by amixer according to an exemplary embodiment of the present disclosure.

Referring to FIG. 9, a mixer 700 may include a load portion 710, a firstswitching unit 730 performing a switching operation in response to localoscillation signals LOIp′, LOIn′, LOQp′, and LOQn′, and a secondswitching unit 750 performing a switching operation in response tobaseband signals BBIp′, BBIn′, BBQp′, and BBQn′.

The load portion 710 may be connected between an input node and outputnodes N1 and N2 of a first power voltage VDD and may adjust a magnitudeof an RF signal. The load portion 710 may include a first load L1connected between the input node and a first output node N1 of theexternal power voltage VDD, and a second load L2 connected between theinput node and a second output node N2 of the external power voltageVDD.

When a communications device performs wireless communications using amillimeter wave (mmWave), the first load L1 and the second load L2 maybe implemented as inductors. In an exemplary embodiment, inductance ofthe first load L1 and the second load L2 may be 0.1 nH or higher and 0.5nH or lower, respectively.

When the communications device performs wireless communications using awave of terahertz band, the first load L1 and the second load L2 may beimplemented as microstrip lines.

The first switching unit 730 may perform a switching operation using thelocal oscillation signals LOIp′, LOIn′, LOQp′, and LOQn′ phase-shiftedto a first phase value by an LO multiplexing unit, therebyphase-shifting first and second RF signals TXp and TXn output throughthe first and second output nodes N1 and N2 by the first phase value. Inan exemplary embodiment, the first phase value may be in increments of90-degree unit values, including 0 degrees, 90 degrees, 180 degrees, and270 degrees, for example.

The first switching unit 730 may include first to eighth LO transistorsTLO1 to TLO8. The first to eighth LO transistors TLO1 to TLO8 may beimplemented as PMOS transistors or NMOS transistors, or the like.

The first LO transistor TLO1 may be connected between a third node N3and a seventh node N7, and may perform a switching operation in responseto an I+ oscillation signal LOIp′ input to a gate terminal. The secondLO transistor TLO2 may be connected between a fourth node N4 and aseventh node N7, and may perform a switching operation in response to anI− oscillation signal LOIn′ input to a gate terminal. The third LOtransistor TLO3 may be connected between a third node N3 and an eighthnode N8, and may perform a switching operation in response to an I−oscillation signal LOIn′ input to a gate terminal. The fourth LOtransistor TLO4 may be connected between the fourth node N4 and theeighth node N8, and may perform a switching operation in response to anI+ oscillation signal LOIp′ input to a gate terminal.

The fifth LO transistor TLO5 may be connected between a fifth node N5and a ninth node N9, and may perform a switching operation in responseto a Q+ oscillation signal LOQp′ input to a gate terminal. The sixth LOtransistor TLO6 may be connected between the sixth node N6 and the ninthN9, and may perform a switching operation in accordance with a Q− localoscillation signal LOQn′ input to a gate terminal. The seventh LOtransistor TLO7 may be connected between the fifth node N5 and a tenthnode N10, and may perform a switching operation in accordance with a Q−local oscillation signal LOQn′ input to a gate terminal. The eighth LOtransistor TLO8 may be connected between the sixth node N6 and the tenthnode N10, and may perform a switching operation in accordance with a Q+local oscillation LOQp′ input to a gate terminal.

The second switching unit 750 may perform a switching operation inaccordance with combination of the plurality of baseband signals BBIp′,BBIn′, BBQp′, and BBQn′, thereby phase-shifting the first and second RFsignals TXp and TXn output through the first and second output nodes N1and N2 to a second phase value. In an exemplary embodiment, the secondphase value may be a value equal to or lower than 45 degrees, such as 45degrees, 30 degrees, or the like, for example.

The second switching unit 750 may include first to fourth branches R1 toR4 each including a plurality of transistors. The plurality oftransistors included in the second switching unit 750 may be PMOStransistors or NMOS transistors, or the like.

A first branch R1 may include a plurality of first I-phase transistorsTal to Tan (n is a natural number) and a plurality of first Q-phasetransistors Tb1 to Tbm (m is a natural number), connected in parallelbetween a seventh node N7 and an input node of a second power voltage,lower than the first power voltage VDD, such as a ground voltageterminal, for example. The first I-phase transistors Tal to Tan mayperform a switching operation in response to an I+ baseband signal BBIp′input to a gate terminal of each of the plurality of first I-phasetransistors Tal to Tan. The first Q-phase transistors Tb1 to Tbn mayperform a switching operation in response to a Q+ baseband signal BBQp′input to a gate terminal of each of the first Q-phase transistors Tb1 toTbn.

The I+ baseband signal BBIp′ and the Q+ baseband signal BBQp′ input to aplurality of transistors of the first branch R1 may be coupled to eachother in accordance with the switching operations of the first andsecond LO transistors TLO1 and TLO2 connected to the seventh node N7.Accordingly, an I+ baseband signal BBIp″ phase-shifted to a second phasevalue may be output from the plurality of transistors of the firstbranch R1.

The second branch R2 may include a plurality of second I-phasetransistors Tc1 to Tcn and a plurality of second Q-phase transistors Td1to Tdm connected in parallel between the eighth node N8 and an inputnode of the second power voltage, such as a ground terminal, forexample. The second I-phase transistors Tc1 to Tcn may perform aswitching operation in response to an I− baseband signal BBIn′ input toa gate terminal of each of the second I-phase transistors Tc1 to Tcn.The second Q-phase transistors Td1 to Tdn may perform a switchingoperation in response to a Q− baseband signal BBQn′ input to a gateterminal of each of the second Q-phase transistors Td1 to Tdn.

The I− baseband signal BBIn′ and the Q− baseband signal BBQn′ input tothe plurality of transistors of the second branch R2 may be coupled toeach other in accordance with the switching operations of the third andfourth LO transistors TLO3 and TLO4 connected to the eighth node N8.Accordingly, an I− baseband signal BBIn″ phase-shifted to a second phasevalue may be output from the plurality of transistors of the secondbranch R2.

The phase-shifted I+ baseband signal BBIp″ output from the first branchR1 and the phase-shifted I− baseband signal BBIn″ output from the secondbranch R2 may have a phase difference of 180 degrees, and may thereforebe combined to remove an image signal.

The third branch R3 may include a plurality of third Q-phase transistorsTel to Ten and a plurality of third I-phase transistors Tf1 to Tfm,connected in parallel between a ninth node N9 and an input node of thesecond power voltage, such as a ground terminal, for example. The thirdQ-phase transistors Tel to Ten may perform a switching operation inresponse to the Q+ baseband signal BBQp′ input to a gate terminal ofeach of the third Q-phase transistors Tel to Ten. The third I-phasetransistors Tf1 to Tfm may perform a switching operation in response tothe I− baseband signal BBIn′ input to a gate terminal of each of thethird I-phase transistors Tf1 to Tfm.

The Q+ baseband signal BBQp′ and the I− baseband signal BBIn′ input tothe plurality of transistors of the second branch R2 may be coupled toeach other in accordance with a switching operation of the fifth andsixth LO transistors TLO5 and TLO6 connected to the ninth node N9.Accordingly, a Q+ baseband signal BBQp″ phase-shifted to a second phasevalue may be output from the plurality of transistors of the thirdbranch R3.

The fourth branch R4 may include a plurality of fourth Q-phasetransistors Tg1 to Tgn and a plurality of fourth I-phase transistors Th1to Thm, connected in parallel between the tenth node N10 and an inputnode of the second power voltage, such as a ground terminal, forexample. The fourth Q-phase transistors Tg1 to Tgn may perform aswitching operation in response to the Q− baseband signal BBQn′ input toa gate terminal of each of the fourth Q-phase transistors Tg1 to Tgn.The fourth I-phase transistors Th1 to Thm may perform a switchingoperation in response to the I+ baseband signal BBIp′ input to a gateterminal of each of the fourth I-phase transistors Th1 to Thm.

The Q− baseband signal BBQn′ and I+ baseband signal BBIp′ input to theplurality of transistors of the fourth branch R4 may be coupled to eachother in accordance with a switching operation of the seventh and eighthLO transistors TLO7 and TLO8 connected to the tenth node N10.Accordingly, a Q− baseband signal BBQn″ phase-shifted to a second phasevalue may be output from the plurality of transistors of the fourthbranch R4.

The phase-shifted Q+ baseband signal BBQp″ output from the third branchR3 and the phase-shifted Q− baseband signal BBQn′ output from the fourthbranch R4 may have a phase difference of 180 degrees, and may thereforebe combined to remove an image signal.

A method of phase-shifting of the plurality of baseband signals BBIp′,BBIn′, BBQp′, and BBQn′ performed by the first to fourth branches R1 toR4 may be the same as in FIGS. 10A and 10B.

FIG. 10A illustrates a method of phase-shifting a plurality of basebandsignals BBIp′, BBIn′, BBQp′, and BBQn′ to 45 degrees.

Referring to FIG. 10A along with FIG. 9, a mixer 700 may phase-shift theplurality of baseband signals BBIp′, BBIn′, BBQp′, and BBQn′ by acertain phase value by combining a plurality of pairs of signalsselected from among the plurality of baseband signals BBIp′, BBIn′,BBQp′, and BBQn′ to each other. For example, the mixer 700 may shift aphase of the I+ baseband signal BBIp′ by 45 degrees (=BBIp′×1□45° bycombining the I+ baseband signal BBIp′ to the Q+ baseband signal BBQp′in same magnitude.

In an exemplary embodiment, the mixer 700 may adjust magnitudes of theplurality of baseband signals BBIp′, BBIn′, BBQp′, and BBQn′ to maintainmagnitudes of the plurality of baseband signals BBIp′, BBIn′, BBQp′, andBBQn′ to be the same before and after signal conversion. For example,the mixer 700 may adjust a magnitude of each of the I+ baseband signalBBIp′ and the Q+ baseband signal BBQp′ to be

$\frac{\sqrt{2}}{2}$

times and may combine the signals to each other. A combined signal BBIp″may have a magnitude the same as that of the I+ baseband signal BBIp′and a phase different from that of the I+ baseband signal BBIp′ by 45degrees (BBIp″=BBIp′×1□45°).

In an exemplary embodiment, the mixer 700 may adjust magnitudes of theplurality of baseband signals BBIp′, BBIn′, BBQp′, and BBQn′ input tofirst to fourth branches R1 to R4 by controlling the number oftransistors activated in each of the first to fourth branches R1 to R4.For example, to adjust a magnitude of each of the I+ baseband signalBBIp′ and the Q+ baseband signal BBQp′ to be

$\frac{\sqrt{2}}{2}$

times, the mixer 700 may control the number of transistors of theplurality of transistors included in the first branches R1, whichoperates in response to the I+ baseband signal BBIp′, and the number oftransistors of the plurality of transistors included in the firstbranches R1, which operates in response to the Q+ baseband signal BBQp′,to be number k (k is a natural number smaller than n and m).

To shift a phase of the Q+ baseband signal BBQp′ by 45 degrees, themixer 700 may adjust each of a magnitude of the Q+ baseband signal BBQp′and a magnitude of the I− baseband signal BBIn′ to be

$\frac{\sqrt{2}}{2}$

times and may combine the signals. A combined signal BBQp″ may have amagnitude the same as that of the I+ baseband signal BBIp′ and may havea phase different from that of the I+ baseband signal BBIp′ by 135degrees (BBQp″=BBIp′×1□135°).

To shift a phase of the I− baseband signal BBIn′ by 45 degrees, themixer 700 may adjust each of a magnitude of the I− baseband signal BBIn′and a magnitude of the Q− baseband signal BBQn′ to be

$\frac{\sqrt{2}}{2}$

times and may combine the signals. A combined signal BBIn″ may have amagnitude the same as that of the I+ baseband signal BBIp′ and may havea phase different from that of the I+ baseband signal BBIp′ by 225degrees (BBIn″=BBIp′×1□225°).

To shift a phase of the Q− baseband signal BBQn′ by 45 degrees, themixer 700 may adjust each of a magnitude of the Q− baseband signal BBQn′and a magnitude of the I+ baseband signal BBIp′ to be

$\frac{\sqrt{2}}{2}$

times and may combine the signals. A combined signal BBQn″ may have amagnitude the same as that of the I+ baseband signal BBIp′ and may havea phase different from that of the I+ baseband signal BBIp′ by 315degrees (BBQn″=BBIp′×1□315°).

The mixer 700 in the exemplary embodiment may implement a phase-shift of90-degree units by phase-shifting of the plurality of local oscillationsignals LOIp, LOIn, LOQp, and LOQn and may implement a phase-shift of 45degrees by phase-shifting of the plurality of baseband signals BBIp′,BBIn′, BBQp′, and BBQn′, thereby providing a phase-shifting function of45-degree units (which are 0 degrees, 45 degrees, 90 degrees, 135degrees, 180 degrees, 225 degrees, 270 degrees, and 315 degrees) withrespect to an RF signal. As the mixer 700 provides a phase-shiftingfunction with respect to an RF signal, a phase-shifter may not benecessary such that the communications device may reduce a signalreduction, an increase of a chip-area, and an increase of currentconsumption, caused by addition of a phase-shifter.

FIG. 10B illustrates a method of phase-shifting a plurality of transmitsignals by 30 degrees and 60 degrees.

Referring to FIG. 10B along with FIG. 9, a mixer 700 may shift phases ofa plurality of baseband signals BBIp′, BBIn′, BBQp′, and BBQn′ by acertain phase value by combining a plurality of pairs of signalsselected from among the plurality of baseband signals BBIp′, BBIn′,BBQp′, and BBQn′. For example, the mixer 700 may adjust a magnitude ofthe I+ baseband signal BBIp′ and a magnitude of the Q+ baseband signalBBQp′ in certain ratio and may combine the signals, thereby shifting aphase of the I+ baseband signal BBIp′ by 30 degrees (=BBIp′×1□30°).

In an exemplary embodiment, the mixer 700 may adjust magnitudes of theplurality of baseband signals BBIp′, BBIn′, BBQp′, and BBQn′ to maintainthe magnitudes of the plurality of baseband signals BBIp′, BBIn′, BBQp′,and BBQn′ to be the same before and after combination. For example, toshift only a phase of the I+ baseband signal BBIp′ by 30 degrees, themixer 700 may adjust a magnitude of the I+ baseband signal BBIp′ to be

$\frac{\sqrt{3}}{2}$

times and may adjust a magnitude of the Q+ baseband signal BBQp′ to be

$\frac{\sqrt{2}}{2}$

times, and may combine the signals. A combined signal BBIp″ may have amagnitude the same as that of the I+ baseband signal BBIp′ and a phasedifferent from that of the I+ baseband signal BBIp′ by 30 degrees(BBIp″=BBIp′×1□30°).

In an exemplary embodiment, the mixer 700 may adjust magnitudes of theplurality of baseband signals BBIp′, BBIn′, BBQp′, and BBQn′ input tofirst to fourth branches R1 to R4, respectively, by controlling thenumber of transistors activated in each of the first to fourth branchesR1 to R4.

To shift a phase of the I+ baseband signal BBIp′ by 60 degrees, themixer 700 may adjust a magnitude of the I+ baseband signal BBIp′ to be ½times and may adjust a magnitude of the Q+ baseband signal BBQp′ to be

$\frac{\sqrt{3}}{2}$

times, and may combine the signals. A combined signal BBQp″ may have amagnitude the same as that of the I+ baseband signal BBIp′ and a phasedifferent from that of the I+ baseband signal BBIp′ by 60 degrees(BBIp″=BBIp′×1□60°).

To shift a phase of the Q+ baseband signal BBQp′ by 30 degrees, themixer 700 may adjust a magnitude of the Q+ baseband signal BBQp′ to be

$\frac{\sqrt{3}}{2}$

times and may adjust a magnitude of the I− baseband signal BBIn′ to be ½times, and may combine the signals. A combined signal BBQp″ may have amagnitude the same as that of the I+ baseband signal BBIp′ and a phasedifferent from that of the I+ baseband signal BBIp′ by 120 degrees(BBQp″=BBIp′×1□120°).

To shift a phase of the Q+ baseband signal BBQp′ by 60 degrees, themixer 700 may adjust a magnitude of the Q+ baseband signal BBQp′ to be ½times and may adjust a magnitude of the I− baseband signal BBIn′ to be

$\frac{\sqrt{3}}{2}$

times, and may combine the signals. A combined signal BBQp″ may have amagnitude the same as that of the I+ baseband signal BBIp′ and a phasedifferent from that of the I+ baseband signal BBIp′ by 150 degrees(BBQp″=BBIp′×1□150°).

To shift a phase of the I− baseband signal BBIn′ by 30 degrees, themixer 700 may adjust a magnitude of the I− baseband signal BBIn′ to be

$\frac{\sqrt{3}}{2}$

times and may adjust a magnitude of the Q− baseband signal BBQn′ to be ½times, and may combine the signals. A combined signal BBIn″ may have amagnitude the same as that of the I+ baseband signal BBIp′ and a phasedifferent from that of the I+ baseband signal BBIp′ by 210 degrees(BBIn″=BBIp′×1□210°).

To shift a phase of the I− baseband signal BBIn′ by 60 degrees, themixer 700 may adjust a magnitude of the I− baseband signal BBIn′ to be ½times and may adjust a magnitude of the Q− baseband signal BBQn′ to be

$\frac{\sqrt{3}}{2}$

times, and may combine the signals. A combined signal BBIn″ may have amagnitude the same as that of the I+ baseband signal BBIp′ and a phasedifferent from that of the I+ baseband signal BBIp′ by 240 degrees(BBIn″=BBIp′×1□240°).

To shift a phase of the Q− baseband signal BBQn′ by 30 degrees, themixer 700 may adjust a magnitude of the Q− baseband signal BBQn′ to be

$\frac{\sqrt{3}}{2}$

times and may adjust a magnitude of the I+ baseband signal BBIp′ to be ½times, and may combine the signals. A combined signal BBQn″ may have amagnitude the same as that of the I+ baseband signal BBIp′ and a phasedifferent from that of the I+ baseband signal BBIp′ by 300 degrees(BBQn″=BBIp′×1□300°).

To shift a phase of the Q− baseband signal BBQn′ by 60 degrees, themixer 700 may adjust a magnitude of the Q− baseband signal BBOn′ to be ½times and may adjust a magnitude of the I+ baseband signal BBIp′ to be

$\frac{\sqrt{3}}{2}$

times, and may combine the signals. A combined signal BBQn″ may have amagnitude the same as that of the I+ baseband signal BBIp′ and a phasedifferent from that of the I+ baseband signal BBIp′ by 330 degrees(BBQn″=BBIp′×1□330°).

The mixer 700 in the exemplary embodiment may implement a phase-shift of90-degree units by phase-shifting of the plurality of local oscillationsignals LOIp, LOIn, LOQp, and LOQn and may implement a phase-shift of 30degrees and 60 degrees by phase-shifting of the plurality of basebandsignals BBIp′, BBIn′, BBQp′, and BBQn′, thereby providing aphase-shifting function of 30-degree units (which are 0 degrees, 30degrees, 60 degrees, 90 degrees, 120 degrees, 150 degrees, 180 degrees,210 degrees, 240 degrees, 270 degrees, 300 degrees, 330 degrees, and 360degrees) with respect to an RF signal.

FIGS. 10A and 10B illustrates the example in which the mixer 700 mayprovide a phase-shifting function of 45-degree units and 30-degree unitswith respect to an RF signal, but an exemplary embodiment thereof is notlimited thereto. Alternatively, the mixer 700 in the exemplaryembodiment may provide a phase-shifting function of 45 or below degreeunits, 20-degree units, for example.

In the description below, a structure of a mixer 371 included in areceiver circuit 370 will be described in greater detail with referenceto FIG. 11.

FIG. 11 illustrates a mixer according to an exemplary embodiment of thepresent disclosure.

Referring to FIG. 11, a mixer 800 may include a load portion 810, afirst switching unit 830, and a second switching unit 850.

The load portion 810 may be connected between an input node and aplurality of output nodes N1 to N4 of a first power voltage VDD and maygenerate a receive baseband signal RBBIp in accordance with of aswitching operation of the first switching unit 830 and the secondswitching unit 850.

The load portion 810 may include first to fourth loads L1 to L4connected between an input node of the first power voltage VDD and thefirst to fourth nodes N1 to N4, respectively. In an exemplaryembodiment, when a communications device including the mixer 800performs wireless communications using a millimeter wave (mmWave), thefirst to fourth nodes N1 to N4 may be implemented as inductive devices.In this case, an inductance value of each of the first to fourth nodesN1 to N4 may be 0.1 nH or higher and 0.5 nH or lower. In an exemplaryembodiment, when the communications device including the mixer 800performs wireless communications using waves of terahertz, the first tofourth nodes N1 to N4 may be implemented as microstrip lines.

The first switching unit 830 may include first to eighth LO transistorsTLO1 to TLO8 performing a switching operation in response to a pluralityof local oscillation signals LOIp′, LOIn′, LOQp′, and LOQn′. The firstto eighth LO transistors TLO1 to TLO8 may be PMOS transistors or NMOStransistors.

The first LO transistor TLO1 may be connected between the fifth node N5and the ninth node N9, and may perform a switching operation in responseto the I+ local oscillation signal LOIp′ input to a gate. The second LOtransistor TLO2 may be connected between the sixth node N6 and the ninthnode N9, and may perform a switching operation in response to the I−local oscillation signal LOIn′ input to a gate. The third LO transistorTLO3 may be connected between the fifth node N5 and the tenth node N10,and may perform a switching operation in response to the I− localoscillation signal LOIn′ input to a gate. The fourth LO transistor TLO4may be connected between the sixth node N6 and the tenth node N10, andmay perform a switching operation in response to the I+ localoscillation signal LOIp′ input to a gate.

The fifth LO transistor TLO5 may be connected between the seventh nodeN7 and the eleventh node N11, and may perform a switching operation inresponse to the Q+ local oscillation signal LOQp′ input to a gate. Thesixth LO transistor TLO6 may be connected to the eighth node N8 and theeleventh node N11, and may perform a switching operation in response tothe Q− local oscillation signal LOQn′ input to a gate. The seventh LOtransistor TLO7 may be connected between the seventh node N7 and thetwelfth node N12, and may perform a switching operation in response tothe Q− local oscillation signal LOQn′ input to a gate. The eighth LOtransistor TLO8 may be connected to the eighth node N8 and the twelfthnode N12, and may perform a switching operation in response to the Q+local oscillation signal LOQp′ input to a gate.

The second switching unit 850 may include first and second transistorsT1 and T2 performing a switching operation in response to a plurality ofRF receive signals RXp and RXn. The first and second transistors T1 andT2 may be PMOS transistors or NMOS transistors.

The first transistor T1 may be connected between the thirteenth node N13and an input node of a second power voltage, lower than the first powervoltage VDD, a ground terminal, for example, and may perform a switchingoperation in response to the first RF receive signal RXp input to agate. The second transistor T2 may be connected between the fourteenthnode N14 and an input node of a second power voltage, and may perform aswitching operation in response to the second RF receive signal RXn.

The mixer 800 may perform an operation of mixing the plurality of localoscillation signals LOIp′, LOIn′, LOQp′, and LOQn′ and the receivesignals RXp and RXn in accordance with the switching operations of thefirst switching unit 830 and the second switching unit 850, and maygenerate a plurality of baseband signals RBBIp, RBBIn, RBBQp, and RBBQn.In an exemplary embodiment, the I+ baseband signal RBBIp, the I−baseband signal RBBIn, the Q+ baseband signal RBBQp, and the Q− basebandsignal RBBQn may be output through the first to fourth nodes N1 to N4,respectively.

In the description below, a method of performing wireless communicationsby a communications device will be described in accordance with anexemplary embodiment with reference to FIGS. 12 and 13.

FIG. 12 illustrates a method of transmitting an RF signal by acommunications device according an exemplary embodiment of the presentdisclosure.

Referring to FIG. 12, in operation S10, the communications device maymultiplex a local oscillation signal generated by a local oscillator andmay shift a phase of the local oscillation signal. In an exemplaryembodiment, the communications device may include a local oscillation(LO) multiplexing unit for multiplexing a local oscillation signal, andthe LO multiplexing unit may include a multiplexer and an LO bufferincluding a plurality of buffer paths. The detailed description of theLO multiplexing unit is the same as in the exemplary embodimentsdescribed with reference to FIGS. 4 to 8.

In operation S20, the communications device may shift phases of aplurality of transmit baseband signals by combining the plurality oftransmit baseband signals generated from a certain transmit bitstreamand input to a mixer. In an exemplary embodiment, the communicationsdevice may adjust a shifted phase value by adjusting magnitudes of thetransmit baseband signals to be combined. For example, thecommunications device may generate a phase-shift of 45 degrees bycombining two transmit baseband signals intersecting each other in thesame magnitude. Also, the communications device may differently adjustmagnitudes of two transmit baseband signals intersecting each other tobe

$\frac{\sqrt{3}}{2}$

times and ½ times, thereby generating a phase-shift of 30 degrees or 60degrees.

In operation S30, the communications device may generate a plurality ofRF transmit signals by frequency up-conversion of the phase-shiftedtransmit baseband signals using phase-shifted local oscillation signals.In an exemplary embodiment, the plurality of RF transmit signals mayinclude a first RF transmit signal and a second RF transmit signalhaving a phase difference of 180 degrees therebetween.

In operation S40, the communications device may perform wirelesscommunications using the plurality of RF transmit signals generated inthe operation S30. In an exemplary embodiment, the communications devicemay perform transmit-beamforming by forming at least one beam using theplurality of RF transmit signals.

FIG. 13 illustrates a method of receiving an RF signal by acommunications device accordance with an exemplary embodiment of thepresent disclosure.

Referring to FIG. 13, in operation S50, the communications device mayreceive an RF transmit signal from an external entity through anantenna. In an exemplary embodiment, the communications device mayperform receive-beamforming and may receive at least one beam.

In operation S60, the communications device may multiplex a localoscillation signal generated by a local oscillator and may phase-shift aphase of a local oscillation signal. In an exemplary embodiment, thecommunications device may include an LO multiplexing unit formultiplexing the local oscillation signal.

In operation S70, the communications device may generate a plurality ofbaseband signals by frequency down-conversion of an RF receive signalusing the local oscillation signal phase-shifted in the operation S60.In an exemplary embodiment, the plurality of baseband signals may bequadrature signals including in-phase signals and quadrature phases.

In operation S80, the communications device may multiplex the pluralityof baseband signals generated in the operation S70 and may obtain acertain receive bitstream.

The communications device described in the aforementioned exemplaryembodiments with reference to FIGS. 1 to 13 may perform a phase-shiftingfunction through a mixer without a phase-shifter, thereby reducing asignal reduction, an increase of a chip area, and an increase of currentconsumption.

FIG. 14 illustrates an electronic device including a communicationsdevice according to an exemplary embodiment of the present disclosure.

Referring to FIG. 14, an electronic device 1000 may include a display1010, a memory device 1020, a communications device 1030, a processor1040, and others.

The electronic device 1000 may include a smartphone, a tablet PC, asmart wearable device, or the like.

The display 1010 may include an organic light emitting diode (OLED), aliquid crystal display (LCD), a plasma display panel (PDP), or the like,and may display various images on a screen. The display 1010 may alsoprovide a user interface function. For example, the display 1010 mayprovide a means for inputting various commands by a user.

The memory device 1020 may be a storage medium for storing data,multimedia data, or the like, required for operation of the electronicdevice 1000. The memory device 1020 may include a storage device basedon a semiconductor device. For example, the memory device 1020 mayinclude a dynamic random access memory device such as a DRAM, asynchronous DRAM (SDRAM), a double data rate SDRAM (DDR SDRAM), a lowpower double data rate SDRAM (LPDDR SDRAM), a graphics double data rateSDRAM (GDDR SDRAM), a DDR2 SDRAM, a DDR3 SDRAM, a DDR4 SDRAM, or thelike, or a resistive memory device such as a phase change random accessmemory (PRAM), a magnetic random access memory (MRAM), a resistiverandom access memory (RRAM), or the like.

The memory device 1020 may be implemented by a storage device, and mayinclude at least one of a solid-state drive (SSD), a hard disk drive(HDD), and an optical drive (ODD).

The communications device 1030 may include communications devicesdescribed in the exemplary embodiments with reference to FIGS. 1 to 13.For example, as the communications device 1030 includes a mixerperforming a phase-shifting function, performance deterioration such asan increase of signal loss, a decrease of a gain, an increase of currentconsumption, an increase of a chip area, or the like, caused byincluding a separate phase shifter, may be prevented.

The processor 1040 may perform a calculation or a command word, a task,or the like. The processor 1040 may be a central processing unit (CPU)or a microprocessor unit (MCU), a system on chip (SoC), or the like, andmay exchange various data with the display 1010, the memory device 1020,and the communications device 1030 through a bus 1050.

FIGS. 15 and 16 illustrate application examples of a communicationsdevice according to an exemplary embodiment of the present disclosure.

Referring to FIG. 15, a communications device in the exemplaryembodiment may be mounted on a smartphone 1100 and may provide awireless communications function.

The smartphone 1100 may include a body 1110 having a displaying functionand a housing forming an exterior of the smartphone 1100 and providing asupporting function. A display may be arranged on an externally exposedfront side of the body 1110, and various information and images may bedisplayed on the display.

The communications device may be disposed in the smartphone 1100, and anantenna of the communications device may be disposed on each of cornerregions of the smartphone 1100. In an exemplary embodiment, thecommunications device may include an array antenna including a pluralityof antenna elements. The communications device may performtransmit-beamforming by forming at least one beam 1130 having certaindirectivity and emitting the formed beam 1130 through the array antenna.

Referring to FIG. 16, the communications device in the exemplaryembodiment may be disposed in a vehicle 1200, in an engine room 1210,for example, and may provide a wireless communications function.

The vehicle 1200 may perform a self-driving function using thecommunications device. In this case, the communications device disposedin the vehicle 1200 may sense a traffic lane and may determine whetherthe vehicle 1200 deviates from a traffic lane by performing beamformingusing at least one beam 1230.

According to the aforementioned exemplary embodiments, a mixer mayperform frequency up-conversion of a plurality of baseband signals usinga plurality of phase-shifted local oscillation signals, therebygenerating phase-shifted RF signals.

Also, the mixer may generate the phase-shifted RF signals by combiningthe plurality of baseband signals.

Further, the mixer may perform the phase-shifting of an RF signal in alocal oscillation signal area and a baseband signal area in a dividedmanner, thereby simplifying a circuit structure and reducing powerconsumption and a chip area.

Also, according to the aforementioned exemplary embodiments, thecommunications device may perform the multiplexing of all signals on alocal oscillation (LO) buffer terminal before a mixer and a sourceterminal of a baseband signal, thereby reducing signal loss on a mainsignal path and increasing a gain.

While exemplary embodiments have been shown and described above, it willbe apparent to those of ordinary skill in the pertinent art that varioussubstitutions, modifications and variations may be made withoutdeparting from the scope or spirit of the present inventive concept asdefined by the appended claims and their equivalents.

1-27. (canceled)
 28. A communications device, comprising: a modulatorconfigured to generate a plurality of quadrature baseband signals as abaseband signal; a local oscillation signal generator configured togenerate a plurality of first quadrature local oscillation signals as afirst local oscillation signal; a multiplexer or a buffer configured toreceive the plurality of first quadrature local oscillation signals andphase-shift the plurality of first quadrature local oscillation signalsto generate a plurality of second quadrature local oscillation signalsas a second local oscillation signal, wherein the second localoscillation signal is phase-shifted with respect to the first localoscillation signal; a mixer configured to receive the plurality ofsecond quadrature local oscillation signals and the plurality ofquadrature baseband signals, further configured to adjust a magnitude ofan I-phase quadrature baseband signal or a magnitude of a Q-phasequadrature baseband signal, further configured to combine the I-phasequadrature baseband signal and the Q-phase quadrature baseband signal,and further configured to perform a mixing operation with respect to thecombined quadrature baseband signal and at least one of the plurality ofsecond quadrature local oscillation signals.
 29. The communicationsdevice of claim 28, further comprising a receive mixer configured togenerate a plurality of baseband receive signals by down-conversion of aplurality of radio frequency receive signals based on the plurality ofsecond quadrature local oscillation signals.
 30. The communicationsdevice of claim 28, further comprising: an array antenna for performingbeamforming.
 31. The communications device of claim 28, wherein themixer is further configured to generate a radio frequency transmitsignal as a result of the mixing operation.
 32. The communicationsdevice of claim 28, further comprising: a plurality of loads connectedto an output terminal of the mixer.
 33. The communications device ofclaim 32, wherein each of the plurality of loads includes at least onemicrostrip line when the communications device performs wirelesscommunications using a wavelength of substantially terahertz band. 34.The communications device of claim 28, wherein the plurality of firstquadrature local oscillation signals includes an I+ transmit localoscillation signal, an I− transmit local oscillation signal, a Q+transmit local oscillation signal, and a Q− transmit local oscillationsignal, and wherein the multiplexer is configured to select one of theI+ transmit local oscillation signal, the I− transmit local oscillationsignal, the Q+ transmit local oscillation signal, or the Q− transmitlocal oscillation signal, and to output the selected transmit localoscillation signal as one of the plurality of second quadrature localoscillation signals.
 35. The communications device of claim 28, whereinthe plurality of first quadrature local oscillation signals includes anI+ transmit local oscillation signal, an I− transmit local oscillationsignal, a Q+ transmit local oscillation signal, and a Q− transmit localoscillation signal, and wherein the buffer includes first to fourthbuffer paths each including a plurality of buffers, and is configured togenerate the plurality of second quadrature local oscillation signalsbased on a combination of the plurality of first quadrature localoscillation signals input to the first to fourth buffer paths and anactivation status of the first to fourth buffer paths.
 36. Thecommunications device of claim 28, wherein the mixer includes: a firstswitching unit configured to perform a switching operation in responseto the plurality of second quadrature local oscillation signals; and asecond switching unit configured to perform a switching operation inresponse to the plurality of quadrature baseband signals, wherein themixer is configured to phase-shift the plurality of quadrature basebandsignals through a switching operation of the second switching unit. 37.A communications device, comprising: a modulator configured to generatea plurality of baseband signals; a local oscillation signal generatorconfigured to generate a plurality of local oscillation signals; amultiplexer or a buffer configured to receive the plurality of the localoscillation signals and phase-shift the plurality of the localoscillation signals to generate a plurality of source terminal inputsignals wherein a phase difference between the plurality of the localoscillation signals and the plurality of the source terminal inputsignals is 90 degrees; a mixer configured to receive the plurality ofthe source terminal input signals and the plurality of baseband signals,further configured to phase-shift the plurality of the baseband signalsby a value equal to or lower than 45 degrees.
 38. The communicationsdevice of claim 37, wherein the mixer is further configured to perform amixing operation with respect the plurality of source terminal inputsignals and the plurality of phase-shifted baseband signals.
 39. Thecommunications device of claim 37, further comprising a receive mixerconfigured to generate a plurality of baseband receive signals bydown-conversion of a plurality of radio frequency receive signals basedon the plurality of source terminal input signals.
 40. Thecommunications device of claim 37, further comprising: an array antennafor performing beamforming.
 41. The communications device of claim 38,wherein the mixer is further configured to generate a radio frequencytransmit signal as a result of the mixing operation.
 42. Thecommunications device of claim 37, further comprising: a plurality ofloads connected to an output terminal of the mixer.
 43. Thecommunications device of claim 42, wherein each of the plurality ofloads includes at least one microstrip line when the communicationsdevice performs wireless communications using a wavelength ofsubstantially terahertz band.
 44. The communications device of claim 37,wherein the plurality of local oscillation signals includes an I+transmit local oscillation signal, an I− transmit local oscillationsignal, a Q+ transmit local oscillation signal, and a Q− transmit localoscillation signal, and wherein the multiplexer is configured to selectone of the I+ transmit local oscillation signal, the I− transmit localoscillation signal, the Q+ transmit local oscillation signal, or the Q−transmit local oscillation signal, and to output the selected transmitlocal oscillation signal as one of the plurality of source terminalinput signals.
 45. The communications device of claim 37, wherein theplurality of local oscillation signals includes an I+ transmit localoscillation signal, an I− transmit local oscillation signal, a Q+transmit local oscillation signal, and a Q− transmit local oscillationsignal, and wherein the buffer includes first to fourth buffer pathseach including a plurality of buffers, and is configured to generate theplurality of source terminal input signals based on a combination of theplurality of local oscillation signals input to the first to fourthbuffer paths and an activation status of the first to fourth bufferpaths.
 46. The communications device of claim 37, wherein the mixerincludes: a first switching unit configured to perform a switchingoperation in response to the plurality of source terminal input signals;and a second switching unit configured to perform a switching operationin response to the plurality of baseband signals, wherein the mixer isconfigured to phase-shift the plurality of baseband signals through aswitching operation of the second switching unit.
 47. A communicationsdevice, comprising: a modulator configured to generate a plurality offirst baseband signals by modulating a transmit bitstream; a localoscillation signal generator configured to generate a plurality of firstlocal oscillation signals; a multiplexer configured to receive theplurality of first local oscillation signals and multiplex the pluralityof first local oscillation signals to generate a plurality of secondlocal oscillation signals, wherein the plurality of second localoscillation signals are phase-shifted with respect to the plurality offirst local oscillation signals; a mixer configured to generate a radiofrequency transmit signal by up-conversion of the plurality of firstbaseband signals using the plurality of second local oscillationsignals, wherein the mixer is configured to generate a plurality ofsecond baseband signals phase-shifted by a second phase value withrespect to the plurality of first baseband signals by combining theplurality of first baseband signals, and to perform a mixing operationwith respect to the plurality of second baseband signals and theplurality of second local oscillation signals.
 48. The communicationsdevice of claim 47, wherein the mixer includes: a first switching unitconfigured to perform a switching operation in response to the pluralityof second local oscillation signals; and a second switching unitconfigured to perform a switching operation in response to the pluralityof first baseband signals, wherein the plurality of second basebandsignals are generated in response to a switching operation of the secondswitching unit.